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For Russia's customers' sake I would hope there would be multiple changes to the design before it goes into serial production.

Specular return aside (just the pitots themselves have an RCS numerous times larger than the entire F-35 front aspect) the measures to reduce surface discontinuity return on all examples of the pak fa so far are almost non existent.

Still has forward facing dihedral reflectors on the OLS. Still has issues with canopy leading edge and frame. Issues with multiple panel edges on the fuselage sides. Still the massive issue with the discontuities on the trailing edges of the wings and actuators.

Have said it before, in 20 years time it'll mean nothing to be the 8th stealthiest bird in the sky.

I am agree.

This is not a stealth fighter, but a low observable fighter. China fighter J20 seems much better product from stealth way than this t-50.

According to published assessments a tenfold reduction of an aircraft's radar cross section increases its survivability du ring the mission by 40%. Alexander Davidenko, Chief Designer of

The PAK FA at the Sukhoi design bureau says, that the radar cross section of previous generation aircraft, for example the Su,27 amounts to 12 sguare metres, and the American F-22 - some 0.3-0.4 sguare metres, The PAK FA will be in this respect "not worse than the F-22, but close to it", says Davidenko. Meaning that the radar cross section of the PAK FA will be at least 30 times smaller than that of the Su,27, hence its survivability is twice greater.

The fuselage of the T,50 is shaped by facets placed at different angles; in its construction special materials are used. Weapon bay and wheel well doors have 'toothed' edges and the production version will be covered with radiation absorbing skin. According to Alexander Davidsnko. the share of composites in the airframe weight amounts to 25% and in the aircraft overall 70%,

The various panels on the fuselage sides doesnt have any photo frame type RAM treatment like the F-35 and also lack saw tooth edges. Same for the access panels at the base of the all moving vertical tail fins. Not much attention has been paid to the removal of surface discontinuities.They are yet to apply the entire gamut of RAM coatings and shapings on the various panels on the prototype birds .A cost cutting measure and they will most likely apply the full stealth treatment on the pre series S birds.
From the currently available pics of the 511, it is still unclear whether it has full scale ram coatings or is just pratly coated like Borts 058 and 059.

The PAK FA at the Sukhoi design bureau says, that the radar cross section of previous generation aircraft, for example the Su,27 amounts to 12 sguare metres, and the American F-22 - some 0.3-0.4 sguare metres, The PAK FA will be in this respect "not worse than the F-22, but close to it", says Davidenko.

Is the figure of some 0.3-0,4 sqm in VHF or UHF bands ? Almost all sources and publications on the Raptor mention a RCS figure of 0.0001 sqm and even less. Maybe its not that less but the frontal RCS isnt 0.3 to 0.4 sqm either.

When will KTRV going to reveal the new series of air to air and A2G missiles and munitions which have been purpose built for the Su-57. I mean Izd 300 and 810 and the aesa seeker variant of the R-77. ? MAKS 2017 by all means and purposes proved to be dissapointing. There werent any new revealations as far as the Pak-fa is concerned. What are the Tactical missile Corporation guys waiting for ? Atleast they could have shown us something.Even some tid bits would have been welcome.
Been ardently waiting for a long time. And neither was there any new information about Item 30.

ZHUKOVSKY, July 20. /TASS/. Russia will develop a family of air-launched precision cruise missiles before 2020 that will be capable of striking targets at a distance of up to 1,000 kilometers, Tactical Missiles Corporation CEO Boris Obnosov said on Thursday

http://www.rusaviainsider.com/maks-t...kh-38-changes/
MAKS: Tactical Missiles Corporation shows Kh-38 changes
The modified design will almost certainly allow the missile to be carried internally without the need to fold the wing and control surfaces, simplifying the design.
The version on display at the show is the Kh-38MLE, which is fitted with a semi-active laser seeker. The maximum range of the Kh-38 is now said to be at least 50 km, rather than the previously disclosed 40 km

http://www.newsweek.com/russia-milit...cisions-639926
"It is impossible to build a missile-carrying bomber invisible to radars and supersonic at the same time. This is why focus is placed on stealth capabilities. The PAK DA will carry AI-guided missiles with a range of up to 7,000 kilometers (about 4,350 miles) Such a missile can analyze the aerial and radio-radar situation and determine its direction, altitude and speed. We’re already working on such missiles," Bondarev told Russia's official Rossiyskaya Gazeta newspaper in comments translated and analyzed by The Aviationist.

just the pitots themselves have an RCS numerous times larger than the entire F-35 front

This wasn't even on the gimmicks list 12 months ago and now it is being declared that the PITOT tubes, have a higher RCS than the ENTIRE F-35 ! When they havn't even produced evidence of any of this let alone the pitot tubes themselves.

Still has forward facing dihedral reflectors on the OLS. Still has issues with canopy leading edge and frame. Issues with multiple panel edges on the fuselage sides. Still the massive issue with the discontuities on the trailing edges of the wings and actuators.

None of this garbage has ever been addressed by official US or western sources. Show me one govt official say that the Pak Fa has X, Y or Z problem which means we are not actually dealing with a stealth aircraft. This is all fanboy hearsay. This is all being generated by amateur observers.

Why should we waste our time, addressing each of these so called "problems" with the stealth of the Pak Fa ? You either believe that the Russian federation put out a tender for a stealth aircraft and a design team and manufacturer made good on the tender or you don't. And if you don't then you are dealing in conspiracy. Which is fine. Just don't pretend that it is up to YOU to decide the designation of the su 57.

@RALL
I am agree.

This is not a stealth fighter

So do you believe Russia was not capable of designing a stealth aircraft ? Or do you think they should have hired some forum posters to help get things straight to make sure the aircraft was stealth ?

This is the kind of analysis people are using to determine that the Pak Fa is not stealth. And that the whole Pak Fa program is a conspiracy.

Look at the various panels will you. Their edges havent been treated . The slightest gap or discontinuity between a panel and the adjacent surface can generate diffraction waves and facilitate the reflection of incoming waves.

I havent ever said that pak-fa aint stealthy or the Russians arent capable. I have more faith in JSC Sukhoi engineers than in arm chair air marshals,generals and analysts who in their infinite wisdom will say that the Pak-fa isnt stealthy at all,it cannot supercruise,it lacks sensor fusion and blah blah. I was only stating that a few more things need to be done before the jet becomes operational in order to reduce its RCS. And in all probability Sukhoi will apply those RAM coatings and do the necessary changes in the pre serial birds. Maybe they are doing so on 510 and thats why it got delayed .

This wasn't even on the gimmicks list 12 months ago and now it is being declared that the PITOT tubes, have a higher RCS than the ENTIRE F-35 ! When they havn't even produced evidence of any of this let alone the pitot tubes themselves.

These are prototypes and they are using them for envelope extension and various other tests. These pitots will surely dissappear in the serial birds.

I'm no expert on sensors but I have a pic in front of me and the tip looks like steel.

F 22 was supposed to have shaved and flush sensors but the idea was shelved to save money says F16.net F22 thread

ADPs cannot be flush mounted since they have to to be "in" the air-stream in order to get the best data. As long as they are faceted & are edge aligned with the rest of the airframe, it does not matter what they are made of.

Not really, full 360° average RCS value doesn't say anything about the RCS in the desired direction such as frontal and tail aspect. When you fly toward a radar, it cannot see your tail or side aspect RCS either.
The side aspect RCS could be extremely high but still doesn't affect the operation of stealth fighter significantly, but the same cannot be said about frontal or tail aspects.

Also, while there are many radar scattering charts for F-22, F-35, J-20 available in public domain, all of them considered the whole aircraft as fully reflective metal surface as radar absorption of classified RAM are not available, it is also the case for radar absorbing structures. So you should take them all with a grain of salt.

Why should we waste our time, addressing each of these so called "problems" with the stealth of the Pak Fa ? You either believe that the Russian federation put out a tender for a stealth aircraft and a design team and manufacturer made good on the tender or you don't. And if you don't then you are dealing in conspiracy.
This is the kind of analysis people are using to determine that the Pak Fa is not stealth. And that the whole Pak Fa program is a conspiracy

No one said Su-57 isn't a stealth aircraft, it is your insecurity talking again. Radisconnect talked about the big pitot tube because that will be removed in production version, like for US aircraft. Arihant talked about the square panels because serrated panels are used to reduce effect of surface diffraction, so production version will likely use a different shape. None of that are wrong or a conspiracy. You need to stop with the ridiculous attitude every time people don't compliment Su-57.

I trust Russian specialists in this field to Lagarkov and Pogosyan. They say that a fifth generation fighter, due to constructive features, can not have a RCS below 0.3 m2

That would be like saying USA engineers and specialists doesn't know what they talking about, even when it comes to their own aircraft which they obviously have access to all of its classified information and can literally test it anytime they want
Secondly, average 360° radar cross section value really doesn't tell you anything useful. Two aircraft, one with frontal RCS of -30dBsm and side aspect RCS of 40 dBsm will operate very different from the other with all around RCS of 10 dBsm, even if they have the same average RCS.

Furthermore, RCS value of 0.3 m2 also doesn't explained what happened in recent Red, Green Flag exercises when various fighters, AWACs and SAM radar working together still unable to detect F-22/35
. You need to reduce RCS by 10 times for 44% radar detection range reduction. 0.3 m2 is only around 3 times smaller than 1m2 (RCS of small aircraft like F-16, F-5, Mig-21, some say Su-35 with RAM is also that range). It doesn't make any sense that stealth aircraft could be that much more effective with such a modest RCS reduction. If what they said is true there is also no point for the luneburg lens on F-22/35

Not really, full 360° average RCS value doesn't say anything about the RCS in the desired direction such as frontal and tail aspect. When you fly toward a radar, it cannot see your tail or side aspect RCS either.
The side aspect RCS could be extremely high but still doesn't affect the operation of stealth fighter significantly, but the same cannot be said about frontal or tail aspects

Not really even in your case.
Average mean exactly that there are a wide array of angles in which the RCS is even superior, so while there are the possibility to turn the plane to face the most relevant threat the angles in which it happen are actually quite narrow so it would be of not any help in case of different radars scanning the area at the same time from different angles.
What you are descriving is instead a situation more akin to the first/second generations of AD systems with fixed installations, knew in advance, single band radars than to corrent century ones with higly mobile batteries, bistatic receivers, frequency hopping emitters, scoot and scoop tactics and so on.
Actually a plane starting for a mission against such systems would not know in advance from where the menace would stem out: they coud even decide not to show the great part of their own asset until the attacking planes are deep inside their own territory and suddenly pop out all together when they are coming back.

The positive thing is that Russians say the F-22 can only do 0,3m² and they can't do better with the Su-57, but still tactically worth it to go for stealth. There is some kind of honesty in that statement.

What is almost useless are statements like: Lockheed says the F-35 has the size of a pea.
Or Patriot and legacy Soviet radar systems such as the Thin Shield could not detect F-22 during U.S exercises.
Or because RAM/RAS is classified it could have a enormous effect magnitudes higher than what is known from publications and studies.

If Russians claim -15 dbsm reduction for F-22 and Su-57 and ~-3 dbsm is known for RAM. Go for maybe -20 dbsm shape and -10 dbsm RAM to achieve -20 dbsm (30dbsm reduction) overall total RCS in the best case (30 times lower than the Russian claim). But taking LM values such as the -50 dbsm total for F-35 is so different, that laws of physics must have been brocken.

You and another did say that earlier in the thread. But I'll accept that as a retraction.

I was only stating that a few more things need to be done before the jet becomes operational in order to reduce its RCS

.

It is your opinion, based on internet pictures. The way you word it, implies that what you are saying is fact, and that everyone agrees with you. Let me tell you. Not everyone agrees with you nor are these facts.

"The Pak Fa has an issue around the canopy and some spaces in the panel work at the back, therefore , we don't have to worry about countering a stealth aircraft from Russia. We should only apply ourselves to counter China"- Said no US official ever.

Not really even in your case.
Average mean exactly that there are a wide array of angles in which the RCS is even superior, so while there are the possibility to turn the plane to face the most relevant threat the angles in which it happen are actually quite narrow so it would be of not any help in case of different radars scanning the area at the same time from different angles.

No, the main purpose of unique shaping on stealth fighters, bombers is literally to deflect radar reflection away from the source. The shape doesn't really absorb radar waves, it only deflect them towards new direction instead of straight back(unless we talking about radar absorbing structure). In others words, you can have the same average 360° RCS for a stealth fighter shape and a conventional fighter shape, but obviously stealth design is better for AD penetration because it reduces RCS significantly from most desired direction.
Spread out SAM and fighters so that you can always illuminate stealth aircraft from their vulnerable aspects are easier said than done. It generally means you need to spread your force over much wider area (fighters, radars located 100-200 km from each other), that makes each defense node more vulnerable to saturation attack.

Originally Posted by Marcellogo

What you are descriving is instead a situation more akin to the first/second generations of AD systems with fixed installations, knew in advance, single band radars than to corrent century ones with higly mobile batteries, bistatic receivers, frequency hopping emitters, scoot and scoop tactics and so on.
Actually a plane starting for a mission against such systems would not know in advance from where the menace would stem out: they coud even decide not to show the great part of their own asset until the attacking planes are deep inside their own territory and suddenly pop out all together when they are coming back.

Not really, frequency hopping isn't new. And even very old SAM systems like Sa-75, Sa-5 has different radars working at different frequencies. It is actually quite rare for medium-long range surface to air systems to use single radar band. Even old AWACs radar operate at very different frequency from fighters radar. Battlefield with different radars operates at different frequency isn't some recent invention.
What relatively new is that new long range air defense are much more mobile than their legacy counterpart. But they are still not as mobile as a short range anti air system. You cannot expect an S-400 to shoot on the move like a ToR-m1. Force reallocation for ground force is still no where as quick or as flexible as force reallocation for an air force. Also, tactics go both ways, ground air defense can turn off their radar and stay silent for close range ambush, but air force can also jam communications, uses decoys to reduce frequent of such ambush.

What is almost useless are statements like: Lockheed says the F-35 has the size of a pea.
Or Patriot and legacy Soviet radar systems such as the Thin Shield could not detect F-22 during U.S exercises.
Or because RAM/RAS is classified it could have a enormous effect magnitudes higher than what is known from publications and studies

Pea size RCS is debatable depending on aspect and frequency but
It is a fact that F-22/F-35 were able to remain stealthy in exercise consist of AWACs, fighters and SAM. J-20 did the same in Chinese exercises as far as i know.
It is also a fact that we don't know performance of RAS or RAM used on either aircraft.
Statement like average RCS =0.3-0.4 m2 is almost useless since it doesn't give any indication about how good they are at penetrating air defense. That value is around 2-3 times smaller than a legacy F-16, Mig-21,F-5 which give you at most 26% detection range reduction.

Originally Posted by PeeD

If Russians claim -15 dbsm reduction for F-22 and Su-57 and ~-3 dbsm is known for RAM. But taking LM values such as the -50 dbsm total for F-35 is so different

Firstly, 0.3-0.4 m2 isn't equal to -15dBsm
Second, most RAM give more than -3dBsm
Thirdly, no one ever said F-35 has total RCS =-50 dBsm

P/S: i don't mean that PAK-FA RCS =0.3 m2 while F-22/35 RCS=0.001m2. Iam saying that RCS from desired aspects such as frontal of all stealth fighter must be much smaller than 0.3-0.4 m2 based on what they demonstrated.

It is fine to criticize the su 57 and fine for people to make the case that the F 22 or F 35 have better stealth than it.

But that's not what some people are doing. Some people are chipping away at the reputation of the su 57, with little quibbles about the stealth that are emanating out of unofficial sources only (fanboys). And they think that they can use these quibbles to deny it a stealth designation.

The only way this will be solved is if there's an agreed upon criteria for what a stealth designation is. Reasonable people tend to believe that when a govt puts out a tender and wants stealth, that it will get it.

Turkey, S Korea, Japan and Europe all have stealth 5th gen jets in the works. Are all of these jets subject to visual inspection before we designate them stealth too ?

For Reference RCS value , Yefim Gordon in his book quotes RCS of Kh-55/Kh-555s rated with an RCS of 0.1-0.2 m2 while Kh-101 is 0.01 m2 .......So an average RCS of say cruise missile of Kh-55 would be lower than average RCS of F-22/PAK-FA at 0.3-0.4 m2 if one has to quote Russian way of measuring RCS and Kh-101 RCS would be like 1/10 of PAK-FA/F-22 ?

As paralays RCS plot shows, it could be even a true statement for ~2-3° of the front aspect, but it can't be neither average nor frontal 90° average.

Paralays plot shows a quite good capability for ~150° of the front aspect, being sub 1m² and two ~20° gaps on both sides of the boresight being in a tactically useful sub 0,1m² range.
This means that it can reasonably maintain the 0,3m² average 150° frontal aspect RCS even if changing significantly the direction due to maneuvering.
It also means that those two 20° gaps in which the average RCS is 0,05m², can be exploited in a -single threat emitter scenario-, to close in to the target or avoid it.

Now we don't know for sure if RAM is taken into account for those plot values, so add -5 dbsm to those values i.e make the 150° frontal average of 0,3 a 0,1. You still wont achieve frontal aspect "stealth" against such a high power emitter as the AWACS.
Despite statements of system producer such as the Americans and Chinese are next to useless, lets believe them. So in air combat maneuvering training in which F-22/-35 and J-20 can credibly maintain their aspect to the respective AEW assets (0,3m², 150° frontal average), those high power emitters could not detect it? Bear in mind that the "black hole shield" 20° RCS of 0,05-0,03m² is not applicable in a scenario with multiple (maneuvering) enemy emitters, such as a AEW aircraft escorted by fighters.

So then let use take some numbers into consideration. The ground based Big Bird radar, which is certainly more powerful than any AEW emitter, would be able to detect a 0,1m² RCS target at ~190km. Even in a highly unlikely scenario in which the escorting fighters had switched off their radars and the 20° gap, 0,03m² RCS could be exploited, the detection range would still be ~140km. As the AEW radar is not a Big Bird, reduce those range numbers for ~30%.

This shows that such rumors are either myths or the Chinese simulated a heavy-LRAAM shot that killed the AEW aircraft at 100-150km. The latter scenario shows the real tactical applications in which stealth becomes very useful. It is a big asset for air warfare with X- to S-band threat emitters of lower powers than encounters by ground emitters.
It is much less of an asset in a enemy ground based IADS, as it won't make the difference necessary to allow single ship deep strikes (at least not against a near-peer adversary). The Russians seem to have understood this and skipped the efforts necessary for all-aspect LO/VLO in the Su-57. It those frontal 150°, 0,3m² RCS and the tactical 20° gap with 0,05m² RCS that counts (values of course only for X- to S-band airborne emitters).

As paralays RCS plot shows, it could be even a true statement for ~2-3° of the front aspect, but it can't be neither average nor frontal 90° average.
Paralays plot shows a quite good capability for ~150° of the front aspect, being sub 1m² and two ~20° gaps on both sides of the boresight being in a tactically useful sub 0,1m² range.
This means that it can reasonably maintain the 0,3m² average 150° frontal aspect RCS even if changing significantly the direction due to maneuvering.
It also means that those two 20° gaps in which the average RCS is 0,05m², can be exploited in a -single threat emitter scenario-, to close in to the target or avoid it.

Direct front isn't the place with lowest RCS
You don't need an average 90° frontal RCS of -50 dBsm to penetrate air defense, low RCS of around - 30 dBsm in 30-40° frontal cone is more than enough and totally achievable with RAM and shaping.

Originally Posted by PeeD

Now we don't know for sure if RAM is taken into account for those plot values, so add -5 dbsm to those values

We do know for sure that RAM aren't taken into account. Firstly, because they have no access to actual RAM used on these aircraft.
Secondly, it is standard for mesh model, optical simulated radar scattering to use metal surface.
And why do you keep assuming RAM only reduces RCS by -5 dBsm while that clearly not the case for most RAM in Xband range?

Despite statements of system producer such as the Americans and Chinese are next to useless

Still more useful than giving an average value. For your information, average RCS of F-16 in +/-45° frontal cone is 0.52 m2 only 40% bigger than your estimated average for stealth fighters. If we follow the average value thinking then F-22, F-35, J-20, PAK-FA..etc only offer 5-6% radar detection range reduction compared to the good old F-16?

Originally Posted by PeeD

So in air combat maneuvering training in which F-22/-35 and J-20 can credibly maintain their aspect to the respective AEW assets (0,3m², 150° frontal average), those high power emitters could not detect it? Bear in mind that the "black hole shield" 20° RCS of 0,05-0,03m² is not applicable in a scenario with multiple (maneuvering) enemy emitters, such as a AEW aircraft escorted by fighters

0.3 m2 is your assumption, not the real value, don't mistaken between the two.
Bear in mind that 20-30° low RCS region can be used in scenarios with multiple emitters as well. If the distance is 100 km, the cone is 30°, your AWACs and escorts aircraft need to be in 2 group located 57 km from each other so that atleast one of them is outside the cone. Simple geometry. But that simple scenario only applicable if you know the direction where stealth aircraft will attack from before hand. If you don't there is a big chance that stealth fighters will came from unexpected directions where not only your defensive assets is inside their black hole shield, your force is already divided by half.

@ActionJackson a spherical object isn't ideal but when properly treated shouldn't be a huge issue, although faceting would be more ideal (I'm honestly not sure why that's not done, maybe Berkut or Scar can explain?).

EOTS will make radar wave returns, that is why there are sensors and software which helps F-35 pilot to reveal as less of EOTS as possible. Best solution would be as done on F-117 and on PAK-FA, when you don't need it or when you are endangered you simply turn it off and it would rotate 180deg presenting thick RAM threaded backside:

They may use indium-tin-oxide instead of gold. Software you described is a method to ease the mission planning part

One area that the Chinese are almost certainly lacking is what Air Combat Command commander Gen. Herbert “Hawk” Carlisle once described to me as “spike management.” Fifth-generation aircraft such as the F-22 and F-35 have cockpit displays that indicate to the pilot the various angles and ranges from which their aircraft can be detected and tracked by various enemy radars. The pilots use that information to evade the enemy by making sure to avoid zones where they could be detected and engaged. It is a technology that took decades for the United States to master—through a lot of trial and error."